Dies.



w. E. SHEBBOINDY.

DIES. APPLICATION FILED AUG-I3. 1914.

Patented July 20, 1915. 7

I v, Mk

5 S S M H W A TTORNE YS.

UTTE 5 WILLIAM E. SHERBONDY, OFGLEVELANID, oHIo, issielvon, iaY MESNE 'Assrsnivrnnrs- TO THE BIGSLBY 302mm: MANUFACTURING COMPANY, or CLEVELAND, onroyn CORPORATION OF OHIO.

DIES.

ofkwhich I hereby declare the following to be a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

The objects of the inventionare to provide 1 a toolor tools such as a die andpunch for carrying out the'several steps of a method for constructing the shell of a spark plug from a sheet metal blank. H

To produce such an article from sheet hareclearly shown in F1'gs. 3,l, and 5', and

metal having the thickness'of wall and small diameter of a shell for a spark plug requires dies of a peculiar shape and construction, and thinner metal cannot be employed since there must be sufficient thickness left in the a wall to'provide for the internal screw thread and also for the projecting angles of the hexagonal portion, to leave the corners sharp and clean as they would beif formed in the usual manner from bar stock.

v The nature 'of theoperation which must be taken in a successionvof stages to gradually draw the metalinto the desired forms requires, that'the metal shouldfirst be drawn into a cup shaped-form of larger diameter than the finished shell, and that the lower portion of this'cup should be drawn out to reduce it in diameter while the diameter of the upper portion remains substantially the same, and upon the upper portion the hexagon is formed bydrawing it through dies 40 which gradually, reduce it in diameter and simultaneously cause the angles to project and assume the hexagonal shape.-

b This invention has to do with the dies which prepare the cup for the final process of ing the hexagon thereon.

accompanying drawings andspecifically blank intona cup of larger diameter than the finished shell, and Figs. 3, l,-and15."are

similar sections that show the dies which form. the cup ,intothe shape from which the hexagonal shell T can be produced.

' This application i': confinedto thespecific form of dies which elongate land" reducelthe lower portion; of the cup in diameter, while unchanged in diameter;

It has been found by careful experiment that the hexagonal shape of the upper portion of the spark plug eannot'be impressed upon a hollow cylindrical'fblank ,or 'cupb'yf drawing, a blank having'fthe finished outer diameters, and i that the vcup shaped; blank must first be made offa larger diameterand' v afterward be .reduced by: drawi the same through peculiarly formed dies'.

The dies for making the prellmmary form imay be described as follows, together with the dies used in leading up to this step.

drical opening A overwhich the flat piece;

of sheet"metal M is aced, and B is a punch which cuts a disk C .of metal from the sheet M. v i

drical opening 'D f'of less diameter than "the disk andalso provided with ,an annular shoulder D? .againstwhich the disk rests,

and which centers it accurately in relation N to the central-opening'jsinceif the slightest eccentricity should exist in the disk the edges of thecup would. be uneven and an vunsightly product would result.

' E is the punch of less, diameter than the L V die opening; a, a, arethe rounded upper corners of the die opening whicha re" made with an arc sufliciently large to give. a -free flowing movement to the'metal as the punch draws, it through-the'die. Otherwise the no distinct shoulder is formed ,at this point. After the cup has'been formed, 'dies of the character shown in Figs. 3, 4:, and 5 are employed. In these figures E is a die block having a cylindrical, opening, smaller-than the diameter of the cup and having rounded corners at f, 7, upon whiehthe shoulder "of v g'l The diameter 9 "is the same as 'the'originalinside' diameter of the a cup and} the die0 retaining the 'u'pper. portion slibstantially .75 In Fig. 1 A."is adie block having acylin- A 1 In Fig. 2 Di's a dieiblock having a cylinv9 5 metal wouldcrackand become cuseless, hence G is a punch having two diametrs, g

Specification of Letters Patent. at n July 20 1915.. Application filed August 13, 1914. Serial No. 856,585, I

no h a ameter g is the same as the inside diameter of the portion of the cup to be reduced. lhe shoulder g separates these portions of the punch.

5 The length of the reduced portion of the punch should correspond with the desired length of the reduced portion of the cup and the punch and die should be accurately concentric with each other, otherwise one side of the shell will be thicker than the other and one side will be drawn altogether out of proportion to the other, and a perfect hexagon cannot be formed thereon.

Upon the upper portion of the punch is mounted a sleeve die H which encircles the same.

This sleeve die rests upon the upper part of the cup and is provided with an annular projecting edge h which retains the exposed 2'0 portion of the edge of the cup in place while the punch is operating.

, The sleeve die is employed to assist the punch in pushing the metal through the small opening in the die block and tends to prevent the cracking of the metal as the reduction is made over the corners 7, f. The punch must not advance too far or the metal will be weakened between the shoulder and the corners f, f, and a uniform thickness of the lower part is preserved. The upper portion of the punch moves freely in the sleeve die but the sleeve die and punch move together during the latter portion of the stroke so that shortly after the smaller portion of the punch enters the die the sleeve die will begin to push against the edge of the cup and thus assist the punch in drawing out the metal. Ordinarily the V sleeve die will have the effect of somewhat 40 thickening or upsetting the upper portion of the cup, thus preparing it to receive the internal screw thread and the projecting angles; as shown in the figures the punch and I sleeve die are operatively connected by the screw J which has a limited movement in the slot J In Fig. 4 the punch is shown having a still further reduced lower end, thus further elongating and reducing the lower end of the cup while retaining the diameter of the upper portion, substantially unchanged. The opening in the die is also correspondingly smaller.

In Fig. 5 the die and punch are still i .55 further reduced and the radius of the curve of the corner 7, 7, constantly increases in length, since the diameter of the upper portion of the cup remains unchanged while I v the lower portion constantly grows smaller. I After passing through these dies the metal cup is ordinarily so hard as to require annealing before further steps are taken. its many dies of this character can be used as may be necessary to gradually draw the cup into the required portions of diflerent diameter from which a shell for a spark plug can be made.

Having described the invention what I claim as new and desire to secure by Letters Patent is:

1. In dies for forming a cup of two diameters from a sheet metal cup, and for the purpose described, a die block having an opening of less diameter than the cup, a punch having a shoulder, and a portion of reduced diameter, and a die sleeved over said punch, having a limited movement thereon, substantially as described.

2. The combination with a die block having an opening provided with rounded so upper edges, of a punch therefor having a reduced lower end of less diameter than said opening, a shoulder separating the two portions of said punch, and a sleeve encircling the larger portion of said punch and having a predetermined amount of movement thereon.

3. In dies for forming a cup shaped blank from sheet metal, said blank having an upper cylindrical portion and a lower integral portion of reduced diameter, a die block having an opening, the upper corners of which are rounded, a punch having a portion of less diameter than said opening, and a portion of substantially the same diameter as said opening, a shoulder at the juncture of said portions of said punch, and a sleeve operatively attached to the larger portion of said punch and having a limited loose motion thereon, said sleeve engaging the enlarged extremity of said blank.

4. In dies for forming a cup shaped article having a cylindrical upper end and a lower end of reduced diameter, from a on shaped sheet metal blank, a die block having an opening, a punch therefor of less diameter than said opening, said punch 11 aving a portion of larger diameter, a shoulder connecting said portions, a sleeve upon the larger portion of said punch, and operated 1W thereby to engage and compress the upper portion of said blank, and to assist in pushing the forward end of the blank through said die block, and permitting a limited amount of free movement of the sleeve upon said punch 5. In a tool for forming a cup shaped blank of two diameters from a sheet metal cup shaped blank, a die block having an opening with rounded upper corners, a punch having a portion of less diameter than said opening, and a portion of larger diameter, and a device having a limited movement upon said punch for exerting pressure upon the upper edge of said blank to assist in forcing said blank into said die.

6. In a tool for reducing the extremity of a cup shaped blank, and for slightly thickening the upper end thereof, a die having an opening provided with rounded corners, 1%

a punch having a portion of less diameter ofsaid blank and an annular rib encircling than said opening and a larger portion, a the same. I y 10 shoulder intermediate of said portions, a In testimony whereof, I hereunto set my sleeve upon said enlarged portion of said hand this 12 day of August 1914. punch having a limited movement thereon, WILLIAM E. SHERBONDY.

a shoulder on said punch engaging said In presence ofsleeve to drive the same, said sleeve having WM. M. MONROE,

an annular extremity for engaging the edge RALPH W." JEREMIAH.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of IPatents,

, Washington, D. G. 

